Apparatuses for continuously tempering chocolate masses and the like are known. The mass to be tempered is a chocolate mass or a similar mass including chocolates, white chocolates, cacao-containing and fat-containing masses.
Apparatuses for continuously tempering chocolate masses and the like are known from the European Patent Applications No. EP 0 289 849 A2 and EP 0 806 149 A2 and from the European Patent No. 0 472 886 B1. The apparatus includes a tempering column including a plurality of chambers being arranged one above the other and forming a cylinder. The chambers are partly connected to a cooling circuit for a cooling medium, and partly to a heating circuit for a heating medium. A mass chamber is formed between two adjacent liquid chambers, the mass chamber being limited by tempering surfaces. The mass to be tempered flows through the mass chambers. The tempering surfaces are formed by adjacent liquid chambers. Each mass chamber includes a driven stirring or mixing tool including a hub and a plurality of arms protruding in a radial direction with respect to the tempering column, the number of arms usually being in the order between 2 and 4. Each arm includes mixing blades being arranged at its top side and at its bottom side, the mixing blades serving to mix the mass. The mixing blades also fulfil the function of taking the mass off the tempering surfaces. This means that the mixing blades are arranged at the arms to overlap in a radial direction. The mixing blades may have an elongated shape. They may also have a convex or a concave design. On one side of the arms, the shape and the arrangement of the mixing blades is always identical, while on the other side of the arms, the design and the arrangement of the mixing blades is also identical, but opposite to the first side of the arms. The arms may additionally include openings to improve the mixing effect. Besides the taking-off effect, the mixing blades fulfil a mixing function. A substantial conveying motion of the mass through the apparatus and from one mass chamber to another mass chamber is attained by a mass pump pumping the liquid mass through the apparatus. Two adjacent mass chambers are interconnected by a mass passage. The mass passages are alternately arranged radially outside and radially inside with respect to the axis of the tempering column. Each mass passage being arranged radially outside includes a cylindrical bore having a circular cross section, the bore extending through the liquid chamber in an axial direction and being sealed with respect to the tempering medium. A temperature sensor is used to measure and to watch the temperature of the mass. The temperature sensor extends into a mass passage being arranged radially outside of the tempering column. This means that the mass passage is not arranged nearby the driving shaft, and it is not connected to the driving shaft. The temperature sensor is located at a place in which the temperature of the mass is changed upstream and downstream by two tempering surfaces being adjacent to a liquid chamber through which one single tempering mediums flows. The temperature of the mass is not correctly measured at the end of a zone, as this is especially desired for reasons of controlling, since the temperature still changes downstream to the end of the zone. The temperature measured by the temperature sensor may be representative for the actual temperature of the mass at the end of the zone, especially if the apparatus is operated at its nominal output or its calculated output. In case the apparatus operates at a reduced output or at reduced power, the streaming characteristics of the mass flowing through the mass passages being arranged radially outside change. Consequently, another insecurity occurs whether the temperature is representative for the partial load and for the end of the zone.
With respect to the objective of preferably measuring the exact temperature of the mass, it is disadvantageous that, due to the stirring arms including mixing blades, regions in which the mass elements are resident for different periods of time occur at different places of the mass chambers. This may be true upstream between the location of the temperature sensor and the end of the zone. Additionally, the mass particles first entering the apparatus do not necessarily also first exit the apparatus. There is the additional danger that, due to the design of the mixing arms, mass portions remain in a continuous circular movement inside the mass chamber between the mixing arms, and they do not participate in the flowing motion through the apparatus. Different temperatures of the mass may occur in such differently moving mass regions. Thus, an optimum growing of the crystals does not occur, and on the other hand, the temperature of the mass is not measured correctly.
Another apparatus for continuously tempering chocolate masses and the like is known from the European Patent Application No. EP 0 872 187 A1. The tempering column includes flat elements which are arranged one above the other. Usually, a liquid chamber through which a tempering medium flows and a mass chamber for the mass are alternately arranged. A heat stop in form of an insulating separating wall is located between two zones with mass chambers. The insulating separating wall is directly arranged between two mass chambers through which the mass flows, or between a mass chamber and a liquid chamber through which tempering medium flows. Thus, the usable surface of heat transmission is reduced. The mass passages are arranged on the outside alternately spaced apart at 180.degree.. A temperature sensor for the mass extends into a mass passage being arranged radially outside, the mass passage interspersing the insulating separating wall with its circular cross section. Thus, the temperature sensor is advantageously arranged between two zones. In case of a partial load of the apparatus, the streaming or flowing characteristics of the mass change, these changes falsifying the measurement of the temperature.
Another apparatus for continuously tempering chocolate masses and the like is known from U.S. Pat. No. 4,648,315. The tempering column includes flat elements being located one above the other. A liquid chamber through which tempering medium flows and a mass chamber through which the mass flows are alternately arranged. The chambers are designed as disk-like hollow bodies. The liquid chambers are connected to tempering circuits. The mass chambers are interconnected by mass passages, the mass passing from one mass chamber into the adjacent mass chamber in the region of the inner circumference of a driving shaft extending with its axis through the tempering column. Thus, the mass passage between two adjacent mass chambers is arranged radially inside, and it has the shape of an annular gap surrounding the driving shaft. Two disk-like bodies are arranged in each mass chamber, the disk-like bodies being driven by the driving shaft. The two disk-like bodies each include openings for the passage of the mass from the bottom side of the first disk to the top side of the second disk. The openings are arranged at the outer circumference of the disks. The two disk-like bodies include spiral-like stripping ridges being arranged at the sides of the disk-like bodies being adjacent to the tempering surfaces of the adjacent chamber. The stripping ridges are designed to be longer than the radius of the disk, and they are arranged in such a sense of rotation to convey the mass. Two adjacent spiral-like stripping ridges form a continuous channel extending from the outside to the inside and from the inside to the outside, respectively. The mass is moved inside this channel without having the possibility of getting in contact with mass portions of other channels. The mass cannot flow from one channel to another channel. The stripping ridges take the mass off the tempering surfaces without getting in direct contact to the tempering surfaces. The two disk-like bodies include ridges being substantially continuous from the inside to the outside and being arranged at the two adjacent sides inside each mass chamber. The ridges are arranged in a radial direction, and they are provided to attain a mixing effect for the mass. There is the danger of zones getting formed between the disk-like bodies. In these zones, mass could be resident, and it could stay in these zones, so that the mass exclusively flows over the outer sides of the two disk-like bodies being adjacent to the tempering surfaces. A substantial mixing effect of the mass inside the mass chamber is not attained by these two disks. Temperature sensors for the mass are exclusively arranged radially outside in the mass chambers between the two disk-like bodies. Radially outside means that the temperature sensors are not located inside the mass passage which is connected to the driving shaft, but rather in the outer region of the tempering column. Although the location of the temperature sensor is arranged inside a zone, it is never arranged at the end of a zone and between two zones, respectively, so that with this arrangement it is not possible to measure the exact temperature at the end of a zone. Additionally, the measurement of the temperature in case of partial load is negatively influenced by changes of the stream and similar effects.